PetroChina blamed slower Chinese economic growth, stronger gas demand that required bigger imports at high global prices and government controls that limit the company's ability to pass on its costs to consumers.

Growth in the world's second-largest economy slowed to 7.8 percent last year, its lowest rate since the 1990s following a decade of double-digit annual expansion.

In December, a PetroChina subsidiary struck a $2.2 billion deal with Canada's Encana Corp. to explore and develop shale natural gas in Alberta. They agreed to spend $4.1 billion together on drilling and other work over the next four years.

Also in December, PetroChina paid $1.6 billion for BHP Billiton's stakes in two natural gas projects off Australia's west coast.

This month, PetroChina's parent, China National Petroleum Corp., agreed to pay Italy's ENI S.p.A $4.2 billion for a 20 percent stake in a gas field in Mozambique. The two companies also agreed to jointly explore shale gas development at a field in China's southwest.